Implementation of an a2s exporter

.github/workflows/ci.yaml

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+name: CI
+
+on:
+  - push
+  - pull_request
+
+jobs:
+  Test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Go
+        uses: actions/setup-go@v2
+
+      - name: Run Test
+        run: make test
+
+  Lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Run Lint
+        uses: golangci/golangci-lint-action@v2
+
+  Docker:
+    runs-on: ubuntu-latest
+    needs:
+      - Test
+      - Lint
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: armsnyder/a2s-exporter
+
+      - name: Log in to Docker Hub
+        if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+        uses: docker/login-action@v1
+        with:
+          username: armsnyder
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+
+      - name: Docker build
+        if: github.event_name != 'push' || !startsWith(github.ref, 'refs/tags/v')
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: false
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+
+      - name: Docker build and push
+        if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+
+      - name: Sync Docker readme
+        if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+        uses: meeDamian/[email protected]
+        with:
+          pass: ${{ secrets.DOCKERHUB_PASSWORD }}
+          description: true

.gitignore

@@ -1,15 +1,3 @@
-# Binaries for programs and plugins
-*.exe
-*.exe~
-*.dll
-*.so
-*.dylib
-
-# Test binary, built with `go test -c`
-*.test
-
-# Output of the go coverage tool, specifically when used with LiteIDE
-*.out
-
-# Dependency directories (remove the comment below to include it)
-# vendor/
+# IDE
+.idea
+*.iml

.golangci.yaml

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+# https://golangci-lint.run/usage/configuration/
+
+linters-settings:
+  goimports:
+    local-prefixes: github.com/armsnyder/a2s-exporter
+
+linters:
+  enable:
+    - gocritic
+    - gofmt
+    - goimports
+    - golint
+    - misspell
+    - testpackage
+    - unconvert
+    - whitespace

Dockerfile

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+FROM golang:1.16 AS builder
+WORKDIR /build
+COPY go.mod go.sum ./
+RUN go mod download
+COPY internal internal
+COPY *.go .
+RUN GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -ldflags="-w -s" -o /bin/a2s-exporter .
+
+FROM scratch
+COPY --from=builder /bin/a2s-exporter /bin/a2s-exporter
+ENTRYPOINT ["/bin/a2s-exporter"]

Makefile

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+default: build test
+
+lint:
+	golangci-lint run
+
+fix:
+	golangci-lint run --fix
+
+build:
+	go build ./...
+
+test:
+	go test -v -race ./...

README.md

@@ -1,2 +1,69 @@
-# a2s-exporter
-A Prometheus exporter for Steam game servers
+[![CI](https://github.com/armsnyder/a2s-exporter/actions/workflows/ci.yaml/badge.svg)](https://github.com/armsnyder/a2s-exporter/actions/workflows/ci.yaml)
+
+# A2S Exporter
+
+A Prometheus exporter for Steam game server info.
+
+Supports all Steam game servers which speak the UDP-based A2S query protocol, for example:
+
+* Counter-Strike
+* The Forrest
+* Rust
+* Team Fortress 2
+* Valheim
+
+## Usage
+
+The image is hosted on Docker Hub.
+
+```
+docker run --rm -p 9856:9856 armsnyder/a2s-exporter --address myserver.example.com:12345
+```
+
+### Arguments
+
+Arguments may be provided using commandline flags or environment variables.
+
+#### Required
+
+Flag | Variable | Help
+--- | --- | ---
+--address | A2S_EXPORTER_QUERY_ADDRESS | Address of the A2S query server as host:port (This is a separate port from the main server port).
+
+#### Optional
+
+Flag | Variable | Default | Help
+--- | --- | --- | ---
+--port | A2S_EXPORTER_PORT | 9856 | Port for the metrics exporter.
+--path | A2S_EXPORTER_PATH | /metrics | Path for the metrics exporter.
+--namespace | A2S_EXPORTER_NAMESPACE | a2s | Namespace prefix for all exported a2s metrics.
+--a2s-only-metrics | A2S_EXPORTER_A2S_ONLY_METRICS | false | If true, excludes Go runtime and promhttp metrics.
+
+## Exported Metrics
+
+Metrics names are prefixed with a namespace (default `a2s_`).
+
+Name | Help | Labels
+--- | --- | ---
+player_count | Total number of connected players. | server_name
+player_duration | Time (in seconds) player has been connected to the server. | server_name player_name player_index
+player_score | Player's score (usually \"frags\" or \"kills\"). | server_name player_name player_index
+player_the_ship_deaths | Player's deaths in a The Ship server. | server_name player_name player_index
+player_the_ship_money | Player's money in a The Ship server. | server_name player_name player_index
+player_up | Was the last player info query successful. | 
+server_bots | Number of bots on the server. | server_name
+server_info | Non-numerical server info, including server_steam_id and version. The value is 1, and info is in the labels. | server_name map folder game server_type server_os version server_id keywords server_game_id server_steam_id the_ship_mode source_tv_name
+server_max_players | Maximum number of players the server reports it can hold. | server_name
+server_players | Number of players on the server. | server_name
+server_port | The server's game port number. | server_name
+server_protocol | Protocol version used by the server. | server_name
+server_source_tv_port | Spectator port number for SourceTV. | server_name
+server_the_ship_duration | Time (in seconds) before a player is arrested while being witnessed in a The Ship server. | server_name
+server_the_ship_witnesses | The number of witnesses necessary to have a player arrested in a The Ship server. | server_name
+server_up | Was the last server info query successful. | 
+server_vac | Specifies whether the server uses VAC (0 for unsecured, 1 for secured). | server_name
+server_visibility | Indicates whether the server requires a password (0 for public, 1 for private). | server_name
+
+## Credits
+
+This exporter depends on [rumblefrog/go-a2s](https://github.com/rumblefrog/go-a2s) (MIT). Big thanks to them!

go.mod

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+module github.com/armsnyder/a2s-exporter
+
+go 1.16
+
+require (
+	github.com/prometheus/client_golang v1.11.0
+	github.com/prometheus/client_model v0.2.0
+	github.com/rumblefrog/go-a2s v1.0.0
+)